Recently it has become possible for telephone subscribers to own their own telephones, and to connect them to the telephone lines of the operating telephone company. This has created problems in interfacing subscriber equipment with telephone company equipment. The present invention seeks to solve thse problems by the provision of a terminal box which is accessible at one end to the subscriber to permit subscriber telephones to be connected to the telephone company equipment, and which is accessible at the other end only to the telephone company to permit trouble-shooting by the telephone company and, at the same time, to prevent access to equipment of the telephone company by the subscriber. Although the subscriber's end of the terminal box is normally accessible only to the subscriber, the telephone company may gain access to the subscriber's end of the box when necessary, even though the subscriber's end of the box is locked by the subscriber.
The terminal boxes may be provided in a variety of sizes. They are stackable one on top of the other when expansion is needed. Each of the boxes is provided with a removable chassis, or shelf, so that each box may be adapted to handle different numbers of telephones.
Each box may be provided with a test unit at the subscriber's end so that each subscriber can check out their telephones.